decompress: Return better io error for BUF_ERROR

Use new MaxTooSmall. As the comment notes tho, it might be that we
are lacking input as well, but until I figure out how to test for
that case and determine the cause, lets at least return a more
specific error.

2 files changed, 20 insertions, 6 deletions

diff --git a/src/decompress_lzma.cc b/src/decompress_lzma.cc
index 6baea18..299803d 100644
--- a/src/decompress_lzma.cc
+++ b/src/decompress_lzma.cc
@@ -63,9 +63,16 @@ class XzReader : public io::Reader {
       if (!in_eof_)
         buffer_->consume(stream_.next_in - rptr);
     } else {
-      return std::unexpected(
-          ret == LZMA_DATA_ERROR
-          ? io::ReadError::InvalidData : io::ReadError::Error);
+      switch (ret) {
+        case LZMA_DATA_ERROR:
+          return std::unexpected(io::ReadError::InvalidData);
+        case LZMA_BUF_ERROR:
+          // Tricky, could also be because of too little input.
+          // TODO: Improve logic here if we can
+          return std::unexpected(io::ReadError::MaxTooSmall);
+        default:
+          return std::unexpected(io::ReadError::Error);
+      }
     }
     return got;
   }
diff --git a/src/decompress_z.cc b/src/decompress_z.cc
index f9f87ae..e888e77 100644
--- a/src/decompress_z.cc
+++ b/src/decompress_z.cc
@@ -62,9 +62,16 @@ class DecompressReader : public io::Reader {
       if (!in_eof_)
         buffer_->consume(stream_.next_in - rptr);
     } else {
-      return std::unexpected(
-          ret == Z_DATA_ERROR
-          ? io::ReadError::InvalidData : io::ReadError::Error);
+      switch (ret) {
+        case Z_DATA_ERROR:
+          return std::unexpected(io::ReadError::InvalidData);
+        case Z_BUF_ERROR:
+          // Tricky, could also be because of too little input.
+          // TODO: Improve logic here if we can
+          return std::unexpected(io::ReadError::MaxTooSmall);
+        default:
+          return std::unexpected(io::ReadError::Error);
+      }
     }
     return got;
   }